I've heard that some people are sweating out THC. Is this possible?

While trace amounts of THC will be removed in urine and sweat, great deals of it will not be sweat out. You will have to wait and give it time for the THC to remove itself from the body, which can take weeks.

Sweating in itself does not get rid of the THC. It is the higher temperatures that speed up their metabolism along with the high fluid consumption to keep from getting dehydrated that help flush the THC out. However, THC can remain in the body for days, and a "sweat out" will only accelerate the process by a day or two.

No no no! Not possible. THC can be absorbed through the skin but will not come back out! THC only bonds with fats and alcohols which is not something you sweat out. THC will stay in your system for a while and sweating is not a way to expel it.